Method for measuring the weight of bulk goods loaded by a hydraulic excavator

Abstract

The present invention is directed towards a method for measuring the weight of bulk goods loaded or, alternatively, loading performance over time of hydraulic earth moving machines, excavators or similar machines which are provided with a hydraulically operated material loading scoop. Typically, these loading scoops rotate about and are supported on a loading arm. The scoop is controlled and tilted by a hydraulic piston-cylinder unit. The determination of the weight of bulk goods loaded or of the loading performance of the excavator is often required by the operator and the manufacturer of the apparatus, both for the determination of the performance of the apparatus per work shift, or for the computation of the fully loaded weight of a transport vehicle used in carrying away the bulk goods. The measured values used in determining the weight of the loaded material are the pressure in the piston-cylinder unit, arragned between the loading scoop and the loading arm, and an angle defined by the line passing between the pivot point ofthe shovel and the center of gravity of the empty shovel with respect to a horizontal line. These values are fed into a computer, and by using certain predetermined values and a simple force equation, the weight of the contents of the scoop is calculated and then visually indicated. The weight may be accumulated, and then indicated on command, in order to determine the total loaded quantity of bulk goods. Alternatively, the accumulated weight can indicate the loaded performance of the apparatus if displayed at predetermined time intervals.

We claim: 
     
       1. A method of measuring the loaded material of a material loading machine having a hydraulically operable loading arm and a material loading scoop pivotable on said loading arm about a pivot point, wherein said holding scoop and said loading arm are connected by a hydraulic piston-cylinder unit located therebetween and apparatus for measuring the bailing angle defined by the horizontal and a line passing through the pivot point of the scoop and the center of gravity of the empty scoop and for measuring the pressure on said hydraulic piston-cylinder unit comprising the steps of: (a) feeding a computer the following predetermined fixed values; (i) the weight of the empty scoop;   (ii) the distance from the center gravity of the empty scoop to said pivot point;   (iii) the surface area of the piston of the piston-cylinder unit and the moment distance of said piston-cylinder unit to said pivot point;   (iv) the distance from the center of gravity of the load in the scoop to said pivot point;   (v) the angle between the lines connecting the pivot point to the centers of gravity of the empty scoop and the load in the scoop;     (b) loading material into the scoop;   (c) measuring the pressure in said piston-cylinder unit at least in one position of said loading arm;   (d) measuring said bailing angle at the same position of said loading arm;   (e) providing said measured pressure and bailing angle values to said computer;   (f) computing the weight of the loaded material by using said computer which bases its calculations on said fixed predetermined values and said measured pressure and bailing angle values; and   (g) providing an indication of the weight of said loaded material.   
     
     
       2. A method as claimed in claim 1, wherein: (a) said steps (c) and (d) are performed while said loading arm and scoop are momentarily interrupted in their motion.   
     
     
       3. A method as claimed in claim 1, wherein: (a) at least two loads of said material loading machine are measured according to steps (a)-(f) of claim 1; and   (b) said individual weights of said loads are accumulated and then indicated.   
     
     
       4. A method as claimed in claim 3, wherein: (a) said accumulated weights of said loads are indicated at predetermined time intervals.